This invention relates to the field of intravascular medical diagnosis and treatment. More specifically, the present invention relates to an intravascular device for locating the ostium of the coronary sinus in the right atrium of the heart.
Atherosclerosis is a common human ailment arising from the deposition of fatty-like substances, referred to as atheroma or plaque, on the walls of systemic, peripheral, and coronary blood vessels. These plaques restrict the flow of blood through the affected vessels. Of particular concern is when these plaques develop within the blood vessels that feed the muscles of the heart. In healthy hearts, cardiac blood perfusion results from the two coronary arterial vessels, the left and right coronary arteries which perfuse the myocardium from the epicardial surface inward towards the endocardium. The blood flows through the capillary system into the coronary veins and into the right atrium via the coronary sinus. When atherosclerosis occurs within the arteries of the heart it leads to myocardial infarctions, or heart attacks, and ischemia due to reduced blood flow to the heart muscle.
Increasingly, procedures have been designed to investigate, analyze and diagnose the cause of arrhythmias that occur in the heart. Methods to diagnose the cause of certain arrhythmias include connection of a patient to patch leads placed on the chest of the patient to record the electrical activity of the heart. These procedures are commonly called electrocardiograms. However, more specific information with regard to the patient""s arrhythmia can be gained by placing sensing electrodes at specific locations in the heart. Once these electrodes are in a predetermined, precise location within the heart, readings can be taken which will help determine the types of arrhythmias and diagnose the problems of the patient""s heart.
These electrophysiological analyses require the precise placement of the sensing electrodes within the heart. Examples of locations for the placement of these electrodes include designated points within the right atrium, the right ventricle, near the Bundle of His and in the coronary sinus. The coronary sinus is the largest cardiac vein which serves as a venous conduit from smaller veins within the myocardium to the right atrium. The coronary sinus extends from an opening, called ostium, for the coronary sinus in the right atrium, along the posterior of the heart to the left side of the heart along the atrioventricular border.
Catheters have been in use in medical procedures for many years. Recently, catheters have become more commonly used within the heart and vascular system. For example, catheters can be used to reduce or remove vascular deposits, for example used in balloon angioplasty and stent deployment procedures. Treating congestive heart failure (CHF) interventionally is generally performed using multiple devices, such as guiding catheters, guidewires, sheaths, pacemakers and pacing leads, with the goal being the placement of the pacing lead deep into the coronary sinus.
One of the difficulties in performing procedures within the coronary sinus is finding the ostium to the coronary sinus while the heart is beating. There are a number of anatomical structures within the right atrium which can be easily confused with the coronary sinus. Further, these particular features of the heart do not show up well on a fluoroscope, thus making the procedure quite difficult and time consuming for the physician. One of the difficulties in performing procedures within the heart is finding the ostium of the coronary sinus while the heart is beating. Adding to the difficulty is CHF patients generally have enlarged hearts, which tend to change the location of the ostium from that of a normal heart. Using fluoroscopic techniques also do not work well because blood flow out of the vein pushes the contrast media away from the ostium. Current devices used for locating the coronary sinus generally include guiding catheters, electrophysiological catheters and ultrasonic catheters. Electrophysiological catheters are designed to detect electrical activity or signals within a patient""s heart, while ultrasonic catheters incorporate ultrasonic transducer technology to send and receive acoustic signals that are then processed into images. These devices have a number of drawbacks. One major problem is the unstable positioning of electrophysiological catheters inside the right atrium of the heart. When a catheter is not stabilized, the heart""s electrical conduction pattern is difficult to establish and map the coronary sinus. Another significant disadvantage of existing electrophysiological catheters to locate the coronary sinus is that the medical techniques employing these catheters are complicated and time consuming, requiring repeated manipulation and movement of the catheter.
Ultrasonic catheters have disadvantages and limitations similar to those of electrophysiological catheters, including susceptibility to signal loss, extensive operator input, etc. Another limitation of current ultrasonic catheters is that because the ultrasonic crystals are mounted on either the side or end of the catheter body, instability of the catheter tip position can result, making it difficult to localize the particular site.
The disadvantages of current generation electrophysiological and ultrasonic catheters can be overcome by integrating laser Doppler velocimetry (LDV) technology within an intravascular device such as a catheter or a guidewire. Laser Doppler velocimetry is a technique for measuring the speed of small particles. Generally, for LDV measurements, small particles suspended in a fluid are illuminated by a laser beam and the light scattered to various angles is compared to light in a reference beam to determine the Doppler shift of the scattered light. The Doppler shift of the light depends on the speed of the particles and the angle of measurement.
An intravascular device for locating a coronary sinus of a patient""s heart and method of using the same are described. In one embodiment, the intravascular device includes an elongated member having at least one lumen and at least one optical fiber coupled to the elongated member. The optical fiber has a distal end configured to contact with a blood flow within the patient""s heart and a proximal end coupled to a laser Doppler velocimetry system for performing a plurality of laser Doppler velocity measurements of the blood flow within the heart to locate the coronary sinus of the heart. Incorporating LDV technology into an intravascular device such as a catheter or a guidewire system provides diagnostic information of the physiologic environment of the lesion before, during, or after a therapeutic procedure.